1. Field of the Invention
This invention is related to dual slope analog to digital converters and especially to low level dual slope analog to digital converters wherein an automatic zero offset correction circuit is used.
2. Prior Art
Prior art auto-zero dual slope analog to digital converters have used the high gain non-linear comparator amplifier designed to produce either a large positive or negative output signal, also as the zero correcting amplifier resulting in over-correction first in one direction and then in the other direction. When a linear amplifier is inserted ahead of the comparator amplifier for stable zero correcting, then there may occur a delay when the combination is used as a comparator. This delay introduces non-linearity into the dual slope analog to digital conversion transfer function.